Process of dehydrating meats containing fats in a fluid current



W. A. NOEL Aug.. 21, 1946.

PRocEss or' DEHYDRATNG MEA'rs coNTAINING Furs 1N A FLUID CURRENT 4 sheets-sheet 1 Fnd oct.. 12.11945 Wllliom A.Noe|

4 Sheets-Sheet 2 grwwrvkw William A.Noel

W. A. NOEL Aug. 21, 194s.

PROC'SS OF DEHYDRATING MATS CONTAINING FATS IN A`FLUID CURRENT Filed Oct. 12. 1945 Aug. 27, 1946. w, A, NQEL 2,406,395 Pnocnss or' DEHYDRATING'MEATS conTAmNe FATs In A FLUID vCURRENT Fned oct. 12,` 1945 4 sheets-sheet s will'. x ununw nl William A.Noe|

am, 4,4. @7M

Aug. 27, 194s.

W. A. NOEL PROCESS OF DEHYDRATING BEATS CONTAINING FATS IN A FLUID CURRENT Filed 0st. 12. 1943 4 Sheets-Sheet 4 u zg Il ,i

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3mm/m William A.Noel

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Patented Aug. 27, 1946 TArNING'FATs IN A' FLUID CURRENT William Alexander Noel, Washington, D; C., assignor to the United States of America, as represented by theSecretary of Agriculture v Applicatln October 12, 1943, Slfl N0. 505,939 islam. (01.34-1-19) (Granted under` the act of March 3,1883, as

amepaeanpni so, 192s; 37o o. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April v 30, 1928, and the invention herein described, if patented. may be manufactured and used byor `for the Government of the United States of Americaifor governmental purposes without the payment to me of any royalty thereon. e

This invention relates to a method of processing materials and apparatus therefor, with particular reference to the dehydration of. ground 'meats containing fats using a flow of drying gas, such as heated air, for the dehydration. l

According to conventional methods, granular materials to be dehydrated are loaded on trays and placed in a stream' of drying gas. Other methods involve the use of revolving drums, and so forth, in which the materials being treated are agitated. These methodsregulre the use of elaborate equipment and considerable attend-4 ance during operation. v

.In the dehydration, the materials being processed lfrequently are in contact with metal parts, such as tray floors, which are also subjected to the heated drying gas. This results in the metal parts being heated substantially to the dry bulb temperature ofthe dryingr gas, which ordinarilyis considerably above the wet bulbl temperature. In consequence, the dry bulb temperature must be held suillciently low to prevent scorching of the material at the' points of Contact with the metal parts. This limit on the permissible dry bulb temperature limits the rate of dehydration.

The rate of` dehydration is also limited dueto I non-uniformityof vcontact of the processing gas with all surfaces. of the grains of the material, and in addition, thevproducts-are not uniformly treated. Furthermore, the time requiredl in loadingthe trays into a tray-type dehydrator considerably reduces the overall capacity' vofy such apparatus;

This invention has among its objects a method of dehydrating meats containing fats upwardly flaring tube, nearfits lowerend while passing a stream of drying gas upwardly through the tube, iiicontact with the materialat such velocity that it carries the material upwardly, the grains of the material being vsuspended withy in the stream of 'gasfduringudrying following rfats separate from themeat during the drying and removing the fats from the meats, andan apparatus which requires little attendance in use,

which is simple in construction, using but few movable-parts, which treatsally grains of the meats uniformly, and which treats such material at a maximum rate, and such other objects as are apparent from the followingdes'cription and claim. v

In general, vaccording to this invention, the meat in granular form is subjected toY a stream of dryinggas in such manner that the individ-` ual particles areseparated from each other. and suspended within the gas stream substantially out of contact with heatedparts of the apparatus,

scribed, by feeding the granulated meat into an wardly. The grains of'rmaterialare suspended within. this region, and are continuously tumbledsr" aboutVbeing rst bounced upwardly beyoncl.thef-' v` and are' conveyed through the-treating apparatus the material into a- AVenturi;tuloefli'V which they are delivered out at the top of the tube with the flow of drying vgas and are then separated from it. At'its 4lower end,` the tubev communicates with a plenum chamber and the and drain into the .plenum chamber from which they are separately collected; f Fora detailed explanation' of' the invention, reference is made to thefollowing description of the apparatus shown in the accompanying drawings, in which i Figure 1 is a side elevation showing `two units of the apparatus, it being understood that. any desired number-of units may be used, al1 associated in the manner illustrated for the two. certain parts being broken away forv clearness in illustration; i

Figure 2 is a top view of the apparatus as shown in Figure 1, except enlarged and omitting the motor pulley. This provides mean fo feeding 'hrough suitable aperture in its wall'ff' Dryingegasflows through the Venturi tube. and carries Athe ma terial upwardly into the upright processing tube' l1, which flares upwardly, resulting inY a lowering:

of the velocity of the gas as it moves towardfther..

upper end of the tube.v

Assume a constant, properly regulatedveloeityfof a drying gas entering the processing chamber and a moisture containing granular materialito' be dehydrated. The material is'carriedY upwardly a fractional distance within the processing; tube: until it reaches a region where the air force'tending to move it upwardly `is in equilibriumV with.Y the force ofgravity tending to move itldownlevel of equilibrium dueto, their momentum, andvv then falling somewhat below the level, repeatedly.

change in its specific gravity, in the dimensions ofthe grains, in the surface resistance to flow of gas, or to a combination of these changes. Therefore, the material moves upwardly in the processing tube as it is being dehydrated until\ finally it is delivered out at the top through exit conduit Il. Regulation of the velocity of the gas with other factors constant determines the time that the materialfis dried..

The dried material and drying gas then passl tangently into a cyclone collector 25 for separating the processedlmaterial from the gas. The collector hasa cylindrical wall 2i mergingl into a funnel-shaped bottom 22. As the gas and material whirl about in the collector, the material falls into the funnel-shaped botthm. passing around the edge of a centrally disposed baille 23 located beneath the open end of gas exit tube 24.

'I'he material. is delivered from the collector through' delivery conduit 25, either to the outside. if desired, 'or tofurther processing units, a laterwill be explained. a.

From sas exit tube 24 the drying gas passes into conduit 23, through heater 2l, through cori--` duit 2l, into blower 29, which is preferably powered with a variable speed motor 30 and arranged to have variable speed belting coupling with the bloweras by stepped pulleys 3| and 32, and from the blower through plenum -chamber 33, returning to Venturi tube II, the plenum chamber being in communication with the Venturi tube at the lower end of the tube. a

The heater, which may be of any desired type, is here shown 'as a steam radiator 35 having an outlet pipe 36, and a steam inlet pipe 31 equipped with an air-operated valve 38 regulated by 'a thermostat 33, placed in the plenum chamber. Compressed air is supplied through a tube 40 connected between the thermostat and the valve and air supply tube 4l connected to the thermostat in a known manner. This yprovides f or automatic regulation of the dry bulb temperature of the gas. 'l

Thewet bulb temperature is regulated by admitting outside dry air through port 42 controlled by damper valve43 linked to the damper motor '44, which in turn is automatically controlled in a known manner by a hygrostat 45`also placed in the plenum chamber and connected to the damper motor by a tube 45 and to the supply tube 41.

Excess air is exhausted through port 48 controlled by a damper valve 49 manually set by operating rod 50.

Due to the location of ports 42 and 48 on opposite sides of the radiator 35, only the port 42 need be closely'regulated to provide the desired wet bulb temperature. The radiator creates sufcient resistance to-the flow of airso that, upon opening the valve 43, air enters at this p01` and any approximate opening. of port 48 w ch will allow -escape of the replaced air is suili ient.

Adjustment of the air ow other than by varying the blower speed is provided by shut-oil valves and 52 located in conduit 28 and bei tween the plenum chamber 33 andl Venturi tube I3, respectively. f a If it be desired to treat the materials with other gases, such as. sulphur dioxide or flue gases,

' gases being exhausted to the outside after passing through the processing chamber andcollector.

If blanching is desired, a blanching steam admission pipe 55 communicating with the process- .5 ing tube Il near its lower end may be used. Also, pipe 5B may beemployed to\admit steam in case the processing gas is too dry.

A hot water or steam admission pipe 56 may be additionally provided for cleaning purposes. All that is' necessary to clean and sterilize the apparatus is to turn in steamv or hot water and circulate the hot air until the parts are thoroughIy clean and sterile. The resulting wash water runs down the processing tube into the Al5 plenum chamber, from which it is readily drained.

.The description thus far relates to but one unit. Sucha unit may be used by itself either in a continuous process, as described above, or

2li in'a batch process. In the latter case (which may be necessary if the nature of the material being processed is such that it is not altered suillciently while being treated to cause it to be carriedv over with the processing gas, as, for

example, in case of cooking meat at 100 percent relative humidity), a batch is loaded into the processing tube and after a desired interval of treatment, while suspended in the tube, the gas velocity is increased to blow the batch over into $0 the cyclone collector.

By the batch method, if there is some degree of alteration, as is usually the case, it is also possible to separate fractions of the material which are altered the more rapidly from the other fractions, since they can be passed into the collector before materials which are altered the less rapidly. In caseof dehydration of ground meats of non-uniform sizes of the particles, for example, the smaller particles collect' irst.

Also,.with a single unit the same materials may be given separate processing steps in the batch method. For example, a batch of the granular material may be introduced intothe processing tube, be given a nrst treatment-with sulphur dioxide gas, a second treatment with blanching steam, and successive treatments'4 with dehydrating gasat varying relative humiditiesand temperatures. Finally, the treated materials may be fractionatedV as above explained.

In dehydration in this apparatus of meats, liquids, such as fats, separate from the meats, and drain into the plenum chamber. In order to collect and remove them, the plenum chamber is arranged on a decline, in the manner illustrated in Figure 1. VThe liquid materials iiow toward the left-hand end or the chamber and are drained therefrom through a conventional U-tube trap 6U which is of suflicient length to prevent blowing the processing gas out through the U-tube.

60 Thence, the liquids may be collected or returned to the dehydrated materials, as desired.

Incase of cleaning the apparatus, the wash water is also drained out through the U-tube trap, or through a suitable gate 6i, as shown at the left-handend of the plenumchamber in Figure 1.

The Venturi tube I 6 isprovided toform a suction inlet at the point of admission of matethis point.

' Venturi tube in all instances. For example, by terminating the screw of the conveyor short of the exit end of its enclosing pipe in a manner 7 5 illustrated in Figure 1, with many materials a rial from the conveyor I2, and also provides a ,'70 ,means of increasing the velocity of 'the gas at It is not necessary to provide a' packing eiect is obtained at the exit end of the pipe which prevents blowing of the processing gas back through the conveyor. However, it is desirable to provide a restricted passage for the gas at this point in order to obtain a gas velocity the processing chamber of the second unit. De-

GFI

and is similar to the unit above described, similar parts being given similar characters except primed. As shown, the supplementary unit is arranged in such manner to use thesame blower and heater, being connected in parallel with the other unit in the gas-circulating system. How-` ever, the materials pass through the various units in series, according to the particular embodiment illustrated. Thus, the material processed by the ilrst unit feeds from the bottom 22 of the rst collector into the tube 25 and into the Venturi tube i6' of the second unit. By adding units in this manner, increased capacity is obtained, since the materials can thereby be given a partial treatment in each unit and then be passed on to the next unit for more complete treatment.

Gravity feed may be used for conveying the materials from one unit to the next unit if the collectors are elevated, or any other suitable type of conveyor may be employed. In case the Venturi tube is omitted, a one-way feeding valvey 65 is installed in tube 25. Valves suitable for this purpose are known. 'I'he one shown comprises a set of radial ns 66 tlttingly rotatable n \a casing 61 and driven in any convenient manner.v

The ns block oi back passage of gas, but as they rotate material is dumped at the upper inlet of the casing into the pockets between the fins and is dumped out of the pockets at the lower outlet of the casing. Stopping rotation of the ns stops feeding. l

If the last unit be employed to separate the materials fractionally, which is accomplished in the batch process, the prior unit may nevertheless beoperated continuously, since the material may be allowed to collect in its collector andthen be fed as a batch into the succeeding processing chamber. i

In case of dehydrating, the successive umts may be of decreasing size, as shown, since the volume of the material ordinarily decreases as it is dehydrated.

Although the apparatus shown uses but one blower and heater and but one set of controls, in s ome instances it may be desirable to employ a .separate blower, heater and controls for each unit with the materials passing in series through the several units. With such arrangement. several different treatments may be given the materials in a continuous process. For example, the materials may be -gassed with sulphur di'oxide in the rst unit. blanched in the second unit. and dehydrated with varying temperaturesand humidities in the other units, and a cooking or roasting unit may be added.

Such an arrangement is illustrated in Figure 6 showing two units, the :drst of which is providedl with a processing chamber 60, collector 6I, heater 62, blower 83, and plenum chamber 84, and the second with corresponding partshaving the same reference characters except primed. The collector from the tlrst unit is connected to iced into tails of the .several units are similar to details heretofore described in reference to Figures 1-5.

The parts of the apparatus may be constructed from any suitable material, stainless steel or enameled iron being preferable from the standpoint of cleanliness. As shown, opposite walls of the processing tubes are provided with inspection windows 10 in order to observe the materials therein. However, a more desirable construction would be the `use of a transparent material for at least two opposite walls.

As an example of the method using a single unitwlth this type of apparatus having a processing chamber 11 inches by 11 inches at the bottom, 12 inches by 18 inches at the top, and about 18 feet high, 32 pounds of cooked granulated pork with a moisture content of 54 percent was fed into the processing chamber in a batch while passing processing air through the chamber at 200 F., dry bulb, and 155 F., wet bulb, at the rate of about1800 cubic feet per minute. The temperature of the air first fell to about 170 F., but rose to about 200 F. in about 15 minutes. Within about 20 minutes from the time of loading the batch into the processing chamber, the very finely divided particles of dehydrated meats started passing into the collector, and the largest particles passed into it in about 45 mlnutes. 0n test the dehydrated meat showed a vmoisture content of about 7 percent.

the initial drop in temperature possible if preheated materials are fed into the apparatus and a large capacity heater is used.

AMany other tests using the apparatus with variousl other types of materials showed excellent results both as to ease of attending the apparatus and as to the rapidity and uniformity of the processing.

With light materials (the specic gravity of which is well below one) the process of dehydrating is especially applicable, since these materials change their factors, especially decreasing their density with the loss of water, more rapidly than do. heavier materials', with,the result that they are conveyed more readily upwardly in the processing chamber during the processing operation.

Having thus described the invention, what is from one region to a higher region where the gas force tending to move them upwardly is in equilibrium with the force of gravity tending to move them downwardly and whereby the fats separate from the meat and drain into the plenum chamber, and separately collecting the iats from the plenum chamber and the dehydrated 'meat from the tube.

. WILLIAM ALEXANDER NOEL. 

